These are the worst words a professional tennis player can hear. It's like comparing a scientist to Albert Einstein or a painter to Pablo Picasso. It says, "You are very good." But also, "You are derivative." You have talent, but not genius. You will not live up to the ideal. For Grigor Dimitrov, the man most often compared to Federer in recent years, it was irritating.

"It's started to bother me," he said in an interview earlier this year at the Australian Open in Melbourne. "I hear it even if I don't want to. Sometimes I'm on court and it's break point for me or something, and it's, 'Let's go Roger!' And I'm like, `But I'm Grigor.' "

Dimitrov hears his unwanted nickname, "Baby Fed," less and less these days, and he's receiving more praise for his own style and potential. He feels like his own man—and he's playing like it, too.

"The biggest expectation comes from me," he said.

At Wimbledon on Monday, Dimitrov will compete for a spot in the quarterfinals, where he could face defending champion Andy Murray. So far, he has served well, played smart and dazzled with his array of geometry-defying winners.

But Dimitrov has added a new dimension to his game this year: grit. In his third-round match on Friday, he outlasted Alexandr Dolgopolov, one of the game's most creative players, in five sets.

"I knew that the deeper the match goes, the better odds I have of winning it," Dimitrov said afterward. "That fifth set proved a lot to me today."

No one who watches Dimitrov doubts his technique. He's smooth, balanced, light on his feet and always in control of the ball, very much like Federer. But there have been questions aplenty about his resolve. Federer, who has won 17 Grand Slam titles, won his first at age 21. Before this year, Dimitrov, 23 years old, had yet to advance past the third round at a Grand Slam tournament.

Dimitrov, who dates Maria Sharapova, won a total of three matches at the four majors in 2013. He lost in the first round at the U.S. Open, and then dropped his next two matches, in Beijing and Shanghai. In October, he hired Roger Rasheed, known for his fitness training, as his coach.

"It's a pretty brutal culture that I deliver," said Rasheed, who used to coach Lleyton Hewitt, in an interview earlier this year. "I could make you vomit in a minute."

Dimitrov has embraced the pain.

"A lot of work. A lot of weights," he said at Wimbledon last week. "He's a very tough but fair man in the end of the day. And I love to work."

Soon after he hired Rasheed, Dimitrov won his first title. In Australia this year, he reached the quarterfinals, where he lost to Rafael Nadal, the eventual finalist, in four sets. He disappointed at the French Open—he lost in the first round—but has won three titles so far this season, including one on grass at Queen's Club prior to Wimbledon. Dimitrov has already won 33 matches in 2014, after winning 37, a career high, all of last year.

Rasheed's approach to training is simple: suffer or don't bother.

"If you're not prepared to be redlined in the off season, well then, don't turn up," he said. "I don't want to hear any excuses."

Dimitrov isn't making them. He sounds more like someone who has developed an addiction.

In tennis, beautiful strokes are both a blessing and a burden. Fans love them. So do coaches and scouts. If those strokes don't help a player win, though, the criticism a player endures is usually harsh. Though Dimitrov's game can't be anything less than pretty, he's less concerned with style these days.

"In the end it doesn't matter if you're going to win crappy or if you're going to lose beautiful," he said. "I'd rather win."

Dimitrov will play the unseeded Leonardo Mayer in the fourth round Monday. Another plus: If Dimitrov wins, he'll have a day off on Tuesday before Wednesday's quarterfinals, unlike several players whose matches were canceled or interrupted by rain at the All England Club on Saturday.

The players who will suffer the most are Stanislas Wawrinka, Denis Istomin, John Isner and Feliciano Lopez. They didn't hit a ball on Saturday and now one of them could play a best-of-five-set match three days in a row.

To make the second week less unfair, Wimbledon held back every player on the bottom half of the draw and put a Wimbledon tradition on hold: Usually, every player left in the field plays on the second Monday.

This year, Nadal, Federer and their fourth-round opponents will take Monday off. They will then play their fourth-round matches on Tuesday, and the winners will play in the quarterfinals on Wednesday. Milos Raonic, who hasn't lost a set this tournament, will also have Monday off.

None of this affects Dimitrov, but if he beats Mayer, he'll likely have a bigger problem. To win this tournament, he could well have to beat Murray, top seed Novak Djokovic and either Nadal or Federer in consecutive matches. Those four players have won 38 of the last 42 Grand Slam singles titles.

"I want to create my own legend, my own trademarks," Dimitrov said.

Beating three of the Big Four at Wimbledon would be a remarkable start.

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